页岩气加剧全球变暖
文章来源:未知 文章作者:enread 发布时间:2011-04-13 03:07 字体: [ ]  进入论坛
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Natural gas extracted from shale1(页岩) formations has a greater greenhouse gas footprint - in the form of methane2(甲烷) emissions4 - than conventional gas, oil and coal over a 20 year period. This calls into question the logic5 of its use as a climate-friendly alternative to fossil fuels, according to Robert Howarth and colleagues, from Cornell University in New York. Their work is published online in Springer's journal, Climatic Change Letters. Shale gas has become an increasingly important source of natural gas in the United States over the past decade. Howarth and team evaluated the greenhouse gas footprint of natural gas, obtained by high-volume hydraulic6 fracturing(水力压裂法) of shale formations, focusing on methane emissions. They analyzed7 the most recently published data - in particular, the technical background document on greenhouse gas emissions from the oil and gas industry (EPA 2010), as well as a report on natural gas losses on federal lands from the General Accountability Office (GAO 2010).

They calculated that, overall, during the life cycle of an average shale-gas well, between four to eight percent of the total production of the well is emitted to the atmosphere as methane, via routine venting8 and equipment leaks, as well as with flow-back return fluids during drill out following the fracturing of the shale formations. Routine production and downstream methane emissions are also large, but comparable to those of conventional gas.

Methane is a far more potent9 greenhouse gas than carbon dioxide, but methane also has a 10-fold shorter residence time in the atmosphere. As a result, its effect on global warming falls more rapidly. Methane dominates the greenhouse gas footprint for shale gas on a 20 year horizon, contributing up to three times more than does direct carbon dioxide emission3. At this time scale, the footprint for shale gas is at least 20 percent greater than that for coal, and perhaps twice as great.

Robert Howarth concludes: "The large greenhouse gas footprint of shale gas undercuts the logic of its use as a bridging fuel over coming decades, if the goal is to reduce global warming. The full footprint should be used in planning for alternative energy futures10 that adequately consider global climate change."

Shale gas is extracted by a high-volume hydraulic fracturing (fracking) process. Large volumes of water are forced under pressure into the shale to fracture and re-fracture the rock to boost gas flow. A significant amount of water returns to the surface as flow-back within the first few days to weeks after injection and is accompanied by large quantities of methane.



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1 shale cEvyj     
n.页岩,泥板岩
参考例句:
  • We can extract oil from shale.我们可以从页岩中提取石油。
  • Most of the rock in this mountain is shale.这座山上大部分的岩石都是页岩。
2 methane t1Eyx     
n.甲烷,沼气
参考例句:
  • The blast was caused by pockets of methane gas that ignited.爆炸是由数袋甲烷气体着火引起的。
  • Methane may have extraterrestrial significance.甲烷具有星际意义。
3 emission vjnz4     
n.发出物,散发物;发出,散发
参考例句:
  • Rigorous measures will be taken to reduce the total pollutant emission.采取严格有力措施,降低污染物排放总量。
  • Finally,the way to effectively control particulate emission is pointed out.最后,指出有效降低颗粒排放的方向。
4 emissions 1a87f8769eb755734e056efecb5e2da9     
排放物( emission的名词复数 ); 散发物(尤指气体)
参考例句:
  • Most scientists accept that climate change is linked to carbon emissions. 大多数科学家都相信气候变化与排放的含碳气体有关。
  • Dangerous emissions radiate from plutonium. 危险的辐射物从钚放散出来。
5 logic j0HxI     
n.逻辑(学);逻辑性
参考例句:
  • What sort of logic is that?这是什么逻辑?
  • I don't follow the logic of your argument.我不明白你的论点逻辑性何在。
6 hydraulic AcDzt     
adj.水力的;水压的,液压的;水力学的
参考例句:
  • The boat has no fewer than five hydraulic pumps.这艘船配有不少于5个液压泵。
  • A group of apprentics were operating the hydraulic press.一群学徒正在开动水压机。
7 analyzed 483f1acae53789fbee273a644fdcda80     
v.分析( analyze的过去式和过去分词 );分解;解释;对…进行心理分析
参考例句:
  • The doctors analyzed the blood sample for anemia. 医生们分析了贫血的血样。 来自《简明英汉词典》
  • The young man did not analyze the process of his captivation and enrapturement, for love to him was a mystery and could not be analyzed. 这年轻人没有分析自己蛊惑著迷的过程,因为对他来说,爱是个不可分析的迷。 来自《简明英汉词典》
8 venting bfb798c258dda800004b5c1d9ebef748     
消除; 泄去; 排去; 通风
参考例句:
  • But, unexpectedly, he started venting his spleen on her. 哪知道,老头子说着说着绕到她身上来。 来自汉英文学 - 骆驼祥子
  • So now he's venting his anger on me. 哦,我这才知道原来还是怄我的气。
9 potent C1uzk     
adj.强有力的,有权势的;有效力的
参考例句:
  • The medicine had a potent effect on your disease.这药物对你的病疗效很大。
  • We must account of his potent influence.我们必须考虑他的强有力的影响。
10 futures Isdz1Q     
n.期货,期货交易
参考例句:
  • He continued his operations in cotton futures.他继续进行棉花期货交易。
  • Cotton futures are selling at high prices.棉花期货交易的卖价是很高的。
TAG标签: gas greenhouse shale
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